@solene depends on your threat model. If the threat is more «I forget/lose my passwords» than «I have a risky behavior», then the Browser storage can do great. Once they are ok with that (few month?) migrate to Bitwarden with few rock solid arguments (works almost the same, better security, possibility to share passwords, store files like a copy of passport, no vendor lock-in, etc.).
If the threat is more «I have a risky behavior», the browser storage will end up inside a Stealer log: a pen & paper could be a solution to store passwords safely.

Pen & paper works great with low tech or older people. I failed hard pushing 1Password to my parents, but it was more complex than Bitwarden, I guess.